1. Field of the Invention
The present invention relates to a braking mechanism for use in a taperecorder, videoplayer and other magnetic recording apparatuses.
2. Description of the Prior art
In general in a magnetic recording apparatus using a magnetic tape as recording medium, an idler gear is engaged with an associated reel base in play and quick-winding modes, and the idler gear is released from the reel base and at the same time a reel brake is applied to the reel base.
In a newly developed magnetic recording apparatus using a rotary head a loading block is made to: advance and pull out and wind the tape around the rotary head at the time of transition to the playing position (tape-loading operation); and withdraw and unwind the tape from the rotary head in transition to stopping and ejecting position (tape-unloading operation). The tape-loading is effected simply by moving the loading block, whereas the tape-unloading is effected by rotating the supply reel base in the direction in which the supply reel winds the tape. These tape-loading and unloading requires releasing of the reel brakes from the supply and take up reel bases respectively. Assume that both reel brakes are released to put both reel bases in free position. As mentioned earlier the tape-loading requires no reel base driving whereas the tape-unloading requires reel base driving. For this reason the amount of rotation in tape-loading is different from that in tape-unloading, and therefore the tape position with respect to the head in replaying is different from that in stop or ejection. In an attempt to reduce such deviation in tape position the reel brake is actuated to apply braking force to the take-up reel base whereas the supply reel base is allowed to rotate freely.
Additionally the magnetic recording apparatus has a preload brake to apply a light touch to the supply reel base in quick winding. Specifically when the supply reel base is rotating at an increased speed in quick winding mode, the moment of rotation which is applied to the supply reel base via the tape will increase, and if the supply reel base has a weak resistance to forced rotation, the supply base reel will rotate at a speed which is higher than required with the result that the supply reel supplies an excessive amount of tape which cannot be wound by the take-up reel, thus making the tape loose between the supply and take-up reels. The preload brake is used to make the tape tight between the supply and take-up reels by applying an appropriate constant braking force to the supply reel base to control the rotation of the supply reel.
The reel brakes and preload brake must be controlled to generate different braking forces at different times, and they have separate braking and releasing controls. Accordingly, the required parts increase in number, and the size of the apparatus becomes disadvantageously large. Further disadvantageously the structure of the apparatus is complicated.